Philywebrider, the problem with ProPack and .bum files is if a MAT pose points to a .bum file, and it is actually a .jpg, then ProPack can't convert the .jpg to a .bum file. If a MAT pose points to a .bum file and it is a .bum file, then no problem. If you have ProPack and your MAT poses make references to .bum files and the bump maps are .jpgs I find it easier to open the MAT poses and find and replace .bum with .jpg in a text editor than use vanilla Poser 4 to convert maps.